Blender Subsurface Scattering on Certain Area
One option is to use Vertex Colors:



Go to Object Data in the Properties panel and add a new slot for Vertex Colors. You can then go to Vertex Paint mode and paint wherever you want the subsurface to be.

Unlike Vertex Groups, Vertex Colors can be brought into materials with the Vertex Color node. (Shift+A &gt; Vertex Colors &gt; YourVertexColors).